This paper explores an econometric estimation technique for dynamic linear models. The method combines the analytics of moving average solutions to dynamic models together with computational advantages of the Whittle likelihood. A hypothesis of interest to international and financial economists is represented in the form of cross-equation restrictions and tested under the technique. This paper employs data on Japanese yen- and U.S. dollar-denominated interest rates and yen/dollar exchange rates to examine the hypothesis of uncovered interest parity under rational expectations.